Selecting Window Glass in the USA: ENERGY STAR Southern Zone

The Southern Zone has the hottest summers, so ENERGY STAR performance is focused on saving energy when cooling your home. To do this, heat from the sun must be reflected to prevent it from building up in the home. While the insulation criteria are a bit lower than other zones, heat reflection is at its highest level.

For ENERGY STAR Most Efficient performance, the solar heat gain criteria for window glass remains the same, but insulation is raised to the highest level. For the ultimate in comfort and energy savings, select a Most Efficient window glass package.